Question

Provide an example of a balanced oxidation/reduction reaction. providing an explanation of 250 words showing step by step.

Answer 1

Balance the following chemical reaction by ion – electron method.

  

Solution:

The oxidation is to since the oxidation state of nitrogen atom increases from + 3 to + 5

The oxidation half reaction is      

The reduction is to since the oxidation state of Cr decreases from + 6 to + 3. The reduction half reaction is

Write the two half reactions as shown below

Reduction half reaction                                    oxidation half reaction

                                                        

Balance all the other elements. Except H₂ and O₂

                                                     

Balance hydrogen’s by adding H⁺ ions as the reaction takes place in acid medium.

No hydrogens are present. So need balanced H – atoms.

Balance oxygens by adding necessary number of H₂O molecules on the side deficient in oxygen.

                       

Balance the hydrogens by adding H⁺ ions on the side deficient in hydrogens.

              

Balance the negative charges by adding electrons on the side deficient in negative charges.

       

Multiplying the two half reactions with suitable integers to equalize the number of electrons participating in each of the half reactions.

1 × [6e^⎯ + 14 H⁺ + ] → 2 Cr⁺³ + 7H₂O   [ + H₂O → + 2 H⁺ + 2e^⎯] × 3    

Adding the two half reactions, the overall balanced reaction is obtained.